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Voltage/Frequency Control MCQ Questions & Answers

Voltage/Frequency Control MCQs : This section focuses on the "Voltage/Frequency Control". These Multiple Choice Questions (MCQs) should be practiced to improve the Voltage/Frequency Control skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

Armature reaction is cross-magnetizing in nature due to a resistive load in the synchronous generator.

A. True
B. False

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Question 2

Armature reaction is purely demagnetizing in nature due to a capacitive load in the synchronous motor.

A. True
B. False

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Question 3

Calculate the minimum value of the active power in the cylindrical rotor synchronous machine? (Eb represents armature emf, Vt represents terminal voltage, ? represents rotor angle, X represents reactance)

A. Eb×Vt×sin?÷X
B. 0
C. Eb2×Vt×sin?÷X
D. Eb×Vt÷X

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Question 4

Calculate the power factor if the power angle is 45°.

A. 0.707
B. 0.407
C. 0.608
D. 1

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Question 5

Calculate the reactive power in a 451.26 ? resistor.

A. 1 VAR
B. .6 VAR
C. 0 VAR
D. .9 VAR

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Question 6

Calculate the reactive power in a 725.45 ? resistor.

A. 122.1 VAR
B. 261.1 VAR
C. 0 VAR
D. 199.7 VAR

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Question 7

Calculate the value of the duty cycle if the system is on for 1 sec and off for inf sec.

A. 0
B. 0.89
C. 0.148
D. 0.46

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Question 8

Calculate the value of the short circuit ratio if Voc=78 V, Isc=15 A with field current = 5 A.

A. 5.2
B. 4.8
C. 3.2
D. 1.8

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Question 9

Cylindrical pole machines are less stable than salient rotor machines.

A. True
B. False

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Question 10

SCR determines the stability of the synchronous machine.

A. True
B. False

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Question 11

The phase difference between voltage and current in the purely inductive coil.

A. 20°
B. 90°
C. 40°
D. 88°

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Question 12

The slope of the I-V curve is 180°. Calculate the value of resistance.

A. inf ?
B. .81 ?
C. 45 ?
D. 41.2 ?

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Question 13

The unit of area is m2.

A. True
B. False

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Question 14

Calculate the minimum value of the active power in the cylindrical rotor synchronous machine? (Eb represents armature emf, Vt represents terminal voltage, δ represents rotor angle, X represents reactance)

A. Eb×Vt×sinδ÷X
B. 0
C. Eb2×Vt×sinδ÷X
D. Eb×Vt÷X

View Answer

Question 15

Calculate the reactive power in a 451.26 Ω resistor.

A. 1 VAR
B. .6 VAR
C. 0 VAR
D. .9 VAR

View Answer

Question 16

Calculate the reactive power in a 725.45 Ω resistor.

A. 122.1 VAR
B. 261.1 VAR
C. 0 VAR
D. 199.7 VAR

View Answer

Question 17

The slope of the I-V curve is 180°. Calculate the value of resistance.

A. inf Ω
B. .81 Ω
C. 45 Ω
D. 41.2 Ω

View Answer